Method for Estimating Methane Emissions from Underground Coal Mines: PreliminaryFindings

摘要

The paper discusses the development of an improved method for estimating globalmethane (CH4) emissions from underground coal mining. Since emissions data are presently not available for surface mines, this method is currently restricted to underground mines. The EPA has embarked on a measurements program to quantify CH4 emissions from selected surface mines in the U.S. for later inclusion in this work. CH4 from underground mines can be liberated from three sources: ventilation shafts, gob wells, and crushing operations. Ventilation air, although generally containing 1% or less CH4, contributes most mine emissions because of the enormous volume of air used to ventilate the mine. Gob wells are drilled into the rubble-filled areas formed when the mine roof subsides into the unsupported cavity left behind by longwall mining. Their purpose is to remove CH4 which would otherwise have to be removed by larger and more costly ventilation systems. Currently, no published data exist for the release of CH4 from gob wells. However, preliminary data from the coal mining industry indicate that gob well CH4 emissions could account for a significant fraction of the total emissions associated with longwall mines. The method described in the paper integrates data on coal production, coal properties, coalbed CH4 contents, and coal mine ventilation air emissions from U.S. mines.